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SR 520 - I-5 to Lake Washington

Status

Last updated: February 2018

OverviewThe 2015 Legislature approved funding for SR 520's planned improvements from I-5 to Lake Washington -- the "Rest of the West." These improvements include highway lids in Seattle's Montlake and Roanoke neighborhoods, the south half of a new west approach bridge, a new Portage Bay Bridge, and a second drawbridge over the Montlake Cut. WSDOT is preparing to begin the first phase of construction, known as the Montlake Phase, in late 2018.

Final traffic management plan for the Montlake area Check out the final Neighborhood Traffic Management Plan (pdf 4.3 mb) for the Montlake Phase. This plan, developed by WSDOT and the city of Seattle, includes a refined list of traffic-calming measures planned in the Montlake area, as well as a summary of public feedback and an overview of other city projects in the vicinity.

Montlake Phase noise variance On Jan. 17 we resubmitted our application with the city of Seattle for a noise variance for the upcoming Montlake Phase of SR 520 construction. More information on the application is available on the city of Seattle's website. You also can review our Feb. 15 noise-variance presentation (pdf 3mb) given at a city of Seattle public meeting, or read our Q&A (pdf 539 kb) on the variance.

Why is WSDOT
pursuing this project?
This project, in phases, will complete all planned safety and mobility improvements on SR 520 from Lake Washington to I-5.

The End Result

A safer highway for motorists and transit riders from the replacement of structurally vulnerable bridges.

Improved regional mobility from the addition of dedicated HOV lanes across the entire SR 520 corridor, in both directions.

Greater transportation options with the completion of a regional, cross-lake bicycle/pedestrian path along the entire corridor.

A healthier environment from the creation of treatment systems for highway runoff and other mitigation projects.

Project Benefits

Future improvements to the highway’s western segment in Seattle include:

A new, seismically stronger West Approach Bridge South to carry three lanes of eastbound traffic past Montlake Boulevard to the new floating bridge.

Elements: West Approach Bridge South, Montlake lid and interchange, and land bridge over the highway

Timeline: construction planned to begin in late 2018; estimated duration: 4-5 years

Portage Bay Phase

Elements: Portage Bay Bridge, Roanoke lid, and I-5 connections

Timeline: construction to begin in approximately 2020-2022; estimated duration: 6 years

Montlake Cut Crossing Phase

Elements: second bascule bridge over the Montlake Cut

Timeline: construction to begin as early as 2024; estimated duration: 3 years

The first two phases are each planned to be delivered as design-build contracts. The type of contract for the final phase will be determined in the future.

This graphic (pdf 1 mb) shows the project phasing for the Rest of the West.

Financial Information

In the 2015 Connecting Washington transportation legislation, the state Legislature authorized $1.64 billion in funding to complete SR 520 improvements from Lake Washington to I-5 – the “Rest of the West.” For more information on SR 520 funding, visit the Budget and Performance page.